Depopulating Cell Phone Boards .. what is the best method ?

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ahmadbayoumi

Well-known member
Joined
Sep 21, 2013
Messages
196
Location
Egypt
Dears,

I will buy about 25k of clean (boards with only ICs and without metallic parts) cell phone boards and will start processing them next week.

I have one important question her about removing or depopulating the components on these broads.

I know that there are many ways to do that:

1- Using heat gun but this way will consume a lot of time

2- Using hot sand bath but this also will take some time and will mix the depopulated components with sand

3- Using HCL or diluted HCL.

For me the easiest way is using HCL/diluted HCL as it will not cost me so much and it will be very quick but seems that the only concern her will be if HCL/diluted HCL will be able to dissolve some of the gold in these BCPs or not.

Some say yes and some say no so need your experience here and there is any other way that is more effective and efficient for processing large quantities
 
Sand bath is your best bet.

Heat gun is very time and resource consuming.

HCl will most likely give you more problems than you would like.

Cell phones processed via wet method are very time consuming, but can be rewarding. Like all things in this field, study and patience are key.

There are other ways to skin this cat, im sure.

I believe most who have tried will agree sand bath, or smelting like the big-dogs do. But, to each their own.

Good.luck to you sir.

Topher
 
Thanks Topher :)

But what is the issue in using HCL .. does it affect the gold in the boards ?

I mean why you said that HCL would give more problems than I would like ?

The boards are free of any steal or nay other metal .. Only ICs and capacitors

Here, I'm just trying to find out an efficient way to deal with large quantities .. by other mean, a commercial way for depopulating cell phone boards what will do the required task with minimum resources and maximum output
 
Dears, Still need you help and advise here

Is there any side effect from using HCL to depopulate cell phone boards rather than using to too much acid ?

PLS advise your experience ...
 
ahmadbayoumi said:
Dears, Still need you help and advise here

Is there any side effect from using HCL to depopulate cell phone boards rather than using to too much acid ?

PLS advise your experience ...

Theres a plethora or advice given for you dilemma all over the forums 200,000++ posts.

Its too wasteful of chemicals... Your waste will be a pain to deal with.

You said they are already mainly depopulated though right?
How about some pictures?
 
Thanks again Topher :)

I know that there was 100s of post about this topic but really couldn't reach a conclusion about using HCL to depopulate cell phone broads

Some say it's OK and no problem is using HCL and some say NO as HCL will affect and may dissolve and waste some of the gold in these boards .. so I'm really confused

I have no issue dealing with waste HCL and even I have no issue in cost of the acid so my only concern here would be the effect of using HCL to depopulate these boards on the whole process or the on the yields of the process ..

they are only depopulated from any metallic parts .. but ICs and all other components are still there

I don't have pics now but will share the pics once I got them.

So does depopulating boards with HCL affects the overall yield or have any other issue or side effect on the whole process ?
 
Okay, so i have had my coffee and cigarette and I'm thinking much more clearly now. So-

You say the metal parts have been removed?
So its just the smd's and flatpacks on them?
Or just the big bulky iron and stuff thats left?

-either way, treating with HCl is wasteful
You will run into all sorts of chloride salts that would be best left alone/away from one another... Cadmiun chloride, silver chloride, lead chloride, and thats just the tip of the iceberg.

Do me a favor, go to google.com in the search bar type this EXACTLY:
Goldrefiningforum hcl depopulation

Read the first page or ten of the results... The professionals here have explained it many many times before in a much more elegant way than my simpleton mind can elaborate on.

I would think, depending on HOW they were depopulated previously (which, WHY would they only halfway depopulate them?) it would be much better in the end for you to heat gun or sandbath them then separate and categorize the smds and bgas and process them accordingly.

Everything on the forum is a tried and true method that these fine gentlemen have perfected over the years. I myself dont have the hubris to think that i could better the methods given as guidelines here.

But, i suppose innovation does come around inevitably.
The only issue I see with that, is that HCl depopulation, isnt an innovation, but a means to cut corners....that of which will surely make you pay in the end.

If you are just starting to refine, and you are kicking off your journey with 25kg of cell boards, i would tread lightly, and do my due diligence, and study.
We dont want you to be discouraged, or fail, we want you to thrive. That will not be possible without patience and study.

Please dont think this reply was meant to discourage or belittle, but think of it as a preemptive warning, that the ice you are walking on is thin, and should it break, it would be very very counterproductive as far as you getting, recovering, and refining, the little bit of gold that cell boards contain.

-topher

In regards to your reply-

HCl will never, ever, dissolve gold--(only exception being, when doing harolds wash procedure, and you accidentally leave the gold being cleaned on the hotplate with HCl overnight)

Gold CAN however, get lost, or trapped, by the chloride salts that you would undoubtedly be producing when depopulating the boards itself. Silverchloride, lead chloride can be a pain to get washed completely free of tiny little flakes of gold.

So, HCl wont make you lose the gold, the byproduct metal salts you are creating with the HCl WILL make you lose some gold... How much? I dont know exactly, some? Alot? A little? Perspective and point of view play the part in that answer, while, to me *any* gold lost is alot and too much, but to some, they care not about .004g of gold..

Best of luck to you in your endeavour.

Please keep us posted on your progress, as we all enjoy reading of one another's refining adventures

-topher
 
Many thanks Topher :)

You explained this perfectly .. and Yes, I do care about every 0.01g of my gold ..

Yes, it's time consuming but it worth rather than losing gold

You know, I'm just thinking about splitting the 25Ks boards into tow patches one (5Ks) will go in HCL and the other 20ks will go in sand bath.

This is for seek of experiment and to do the compromise

Sure will post and share my experiment here
 
Topher_osAUrus said:
HCl will never, ever, dissolve gold--(only exception being, when doing harolds wash procedure, and you accidentally leave the gold being cleaned on the hotplate with HCl overnight)
Well... HCl, alone, will not dissolve gold. But HCl and an oxidizer will. HCl, if left open to atmosphere, will absorb enough oxygen to dissolve gold. Not a lot, but a little.

Dave
 
FrugalRefiner said:
Topher_osAUrus said:
HCl will never, ever, dissolve gold--(only exception being, when doing harolds wash procedure, and you accidentally leave the gold being cleaned on the hotplate with HCl overnight)
Well... HCl, alone, will not dissolve gold. But HCl and an oxidizer will. HCl, if left open to atmosphere, will absorb enough oxygen to dissolve gold. Not a lot, but a little.

Dave

So, HCl + O2 from atmosphere is enough to dissolve a.miniscule amount of gold?

Or

Is it the NO2 in the atmosphere that is creating nitrosyl chloride?

I knew that HCl + time (atmosphere) will dissolve copper, it may take a week or 2 for it to oxidize it to copper chloride, but, is heat and atmosphere a determining factor in the gold dissolution as well?

Or, does regular climate temperatures (around 40 c max) not create a high enough temp to aid the little bit of oxidation that may occur with gold in HCl?

And how much might be a little?

I have about 50 more questions to ask, Dave...but, ill leave it to these for now :mrgreen:
 
It's just like the AP process--the 'P' is the peroxide you add in the beginning to kickstart the oxidization reaction, but you can also just leave it out until your HCl absorbs enough oxygen from the environment (or from copper oxide on the surface of the metal). Sure, you might be waiting a while, but it will happen. That's why some like to refer to the process as 'copper leach' instead of 'AP'--it works with or without peroxide.

As Dave said, HCl alone will not dissolve gold, but HCl with the help of an oxidizer can and will dissolve gold. That includes nitric acid, sodium nitrate, bleach, peroxide, and well, plain old oxygen ;)
 
upcyclist said:
It's just like the AP process--the 'P' is the peroxide you add in the beginning to kickstart the oxidization reaction, but you can also just leave it out until your HCl absorbs enough oxygen from the environment (or from copper oxide on the surface of the metal). Sure, you might be waiting a while, but it will happen. That's why some like to refer to the process as 'copper leach' instead of 'AP'--it works with or without peroxide.

As Dave said, HCl alone will not dissolve gold, but HCl with the help of an oxidizer can and will dissolve gold. That includes nitric acid, sodium nitrate, bleach, peroxide, and well, plain old oxygen ;)


That answers my question-Thank you!

I knew it was the O2 in the atmosphere that lead to the initialization of the copper II chloride leach, but since its the NOx that creates nitrosyl chloride when we make AR, I was curious if it was just the oxygen, or Nitrogen in the air we breathe...or any combination there of.. And, I was a tad bit curious as to how much would dissolve... say I had a chunk of 1 troy ounce of gold in a beaker with 1L of HCl, would it dissolve .1 gram after a year? or 10 grams? What if it was 1 troy ounce of precipitated gold?...not that I am going to test that...It's more of a satisfaction of curiosity more than anything.. I like to be a know it all, but to be that, I have to know it all... damn those catch-22's
:p
Thanks upcyclist.

Your answer has lead me to another 50 questions lol. I guess I just might have to throw 10 grams in some HCl, and find out first hand....as I have a feeling, location, air polution, temperature, and 10000 other variables will determine the outcome

-topher, the-inquisitive
 
I don't know if there would be much chance of solid chunk of gold dissolving at all in just HCl. It would be interesting to try. Maybe a small BB in just HCl, and another in HCl with aeration, and let them sit a few months and see what happens.

Let us know what your findings are with that Topher! LOL! :p Just messing with you! :lol:

Though, thank God for stannous chloride! I have managed to put gold powder back in solution with just HCl washes 3 or 4 times so far. One of the times it wasn't even heated. (Before I had read about Lou's cold washes) It was after a 2nd refine, several water washes, then on the 2nd HCl wash it was getting late. I poured in enough acid to cover the powder, put a watch glass on it and went to bed. By the next evening after work I had about a gram back in solution.

What ever the reason(s) may be, it made the lesson even more obvious to me that it always pays to test, test, test!
 
UncleBenBen said:
Though, thank God for stannous chloride! I have managed to put gold powder back in solution with just HCl washes 3 or 4 times so far. One of the times it wasn't even heated. (Before I had read about Lou's cold washes) It was after a 2nd refine, several water washes, then on the 2nd HCl wash it was getting late. I poured in enough acid to cover the powder, put a watch glass on it and went to bed. By the next evening after work I had about a gram back in solution.

What ever the reason(s) may be, it made the lesson even more obvious to me that it always pays to test, test, test!
Hahaha, that's also why often times I run waste through the stockpot, even when I think "there's no way there's any PMs in there..." :wink:
 
upcyclist said:
UncleBenBen said:
Though, thank God for stannous chloride! I have managed to put gold powder back in solution with just HCl washes 3 or 4 times so far. One of the times it wasn't even heated. (Before I had read about Lou's cold washes) It was after a 2nd refine, several water washes, then on the 2nd HCl wash it was getting late. I poured in enough acid to cover the powder, put a watch glass on it and went to bed. By the next evening after work I had about a gram back in solution.

What ever the reason(s) may be, it made the lesson even more obvious to me that it always pays to test, test, test!
Hahaha, that's also why often times I run waste through the stockpot, even when I think "there's no way there's any PMs in there..." :wink:

I too, am the same way.

My gold is my precious! I dont want to lose it... Thats why my shop has like 15 5 gallon buckets in it..
I recently dropped au from a perfect auric chloride solution... Let it sit 3 days... Checked its turpidity, looked good to me... So, i decanted, set it aside..m a weeklater.. I gently stirred the solution for a minute... Then, in the center, a lovely pile of gold agglomerated, equalling .4 grams.

Makes me sad to think of how careless, wreckless, and (most importantly) -*impatient*- i was when i first started.

Which, brings another question -completely unrelated to depop w/HCl.. What causes the re-dissolution when doing the HCl wash as prescribed?

-oxidizers clinging to the glass after ppt?
-oxidizers in the atmosphere?
-heat from the "simmer" on the hotplate?
-something im missing?

-topher, the ever curious
 
Topher.

Minute residues of Nitric cause this. I throw my first acid wash into a jar as the base of my next refine religiously. Alternatively if I have enough remaining liquid that is "dropping" I throw it straight back into that. I used to get all bent out of shape about it however now I just accept it as part of the process.

It's certainly more of an issue if you are refining very small quantities because otherwise the economies of scale kick in.

Jon
 
spaceships said:
Topher.

Minute residues of Nitric cause this. I throw my first acid wash into a jar as the base of my next refine religiously. Alternatively if I have enough remaining liquid that is "dropping" I throw it straight back into that. I used to get all bent out of shape about it however now I just accept it as part of the process.

It's certainly more of an issue if you are refining very small quantities because otherwise the economies of scale kick in.

Jon

Thank you Jon!

One of the first times i refined with AR, i did not use a clean stir stick when stirring my HCl gold wash, and to my surprise, even though i *rinsed* the stir stick off, it still had enough HNO3 (or NOCl?) on it to dissolve HALF of the gold i had in my baby beaker (1.3 grams [estimated])

So, from then on, i was very mindful of good labware hygiene.

And Ben, I most certainly will do that...no joke. It probably wont be for another month or two, but, i will share my experiences here with everyone, just for "S's and G's"

In the name of science!

-toph
 
Topher_osAUrus said:
And Ben, I most certainly will do that...no joke. It probably wont be for another month or two, but, i will share my experiences here with everyone, just for "S's and G's"

Please do, Topher. This enquiring mind would certainly like to know what happens!

With what little I have actually recovered and refined so far, including what I lost, I think I have put gold back in solution with just HCl as much as I haven't. And that is with no nitrates involved at all.
 
I think it may have just dawned on me why I was redissolving so much gold powder with HCl.

It was pretty much all happening around the same time, and I remember being down to maybe 1/2 a liter of HCl left in the jug. If the fumes are heavier than air, then slowly turning the jug to pour what little I needed each time would also pour out fumes. As the fumes poured out they would get replaced with fresh air. The air would get trapped in the jug and with that last little bit of acid sloshing around it probably absorbed a fair amount of O2.

Then there I was, washing gold powder with HCl plus an oxidizer. Or maybe it was something else, but it kind of makes sense in my big ol' cranium.
 
UncleBenBen said:
I think it may have just dawned on me why I was redissolving so much gold powder with HCl.

It was pretty much all happening around the same time, and I remember being down to maybe 1/2 a liter of HCl left in the jug. If the fumes are heavier than air, then slowly turning the jug to pour what little I needed each time would also pour out fumes. As the fumes poured out they would get replaced with fresh air. The air would get trapped in the jug and with that last little bit of acid sloshing around it probably absorbed a fair amount of O2.

Then there I was, washing gold powder with HCl plus an oxidizer. Or maybe it was something else, but it kind of makes sense in my big ol' cranium.

I had that thought once or twice (i think alot of odd thoughts though :lol: )

But, i did just read that some choose (say, do) just cold HCl while doing their precipitated gold wash instead of the hot. As, when HCl gets hot, it breaks down. Which, could, in turn, dissolve some of those good bits at the bottom of the beaker.

And i truly will do that test, i am still fixing up my messes from last years youtube blunders... After i get done with that... And fixing my blunder from 2 nights ago (im stupid, left a solution on the burner and it evaporated to crystal... Then i did it again....idiot)..but, whatever cements out of my buckets, im going to rerun in AR, then melt them down. And those nuggets will be my sacrifice in the name of science.
 
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